Cylinder head coring for overhead valve engines



Nov. 4, 1958 c. B. LEAcH 2,858,587

CYLINDER HEAD CORING FOR OVERHEAD VALVE ENGINES Filed Dec. ,20, 1954 4 Sheets-Sheet 1 INVENTOR ATTORNEY Nov. 4, 1958 E c. B. LEAcH 7 CYLINDER HEAD CORING FOR OVERHEAD VALVE ENGINES Filed Dec. 20, 1954 4 Sheets-Sheet 2 INVENTOR AT TORNEY Nov. 4, 1958 c. B] LEAcH 2,858,537

CYLINDER HEAD CORING FOR OVERHEAD VALVE ENGINES I Filed Dec. 20, 1954 4 Sheets-Sheet 3 ,J/ea /7)' I a}, I I INVENTOR fig faxzfifac BY fla ATTORNEY Nov. 4, 1958 c. B. LEACH CYLINDER HEAD CORING FOR OVERHEAD VALVE ENGINES Filed Dec. 20, 1954 4 Sheets-$heet 4 INVENTOR ATTORNEY United States Patent CYLINDER HEAD CORING-FOROVERHEAD VALVE ENGINES Clayton B. Leach, "Pontiac, Mich, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application fDecemher r20, '1954,.-'Serial"No.' 476,434

8' Claims. ,(CL, 22131) This invention relates to the manufacture ofinternal combustion engines and particularly to a, cylinder head coring arrangement for overhead valvev enginesin-which only a very few cores are used, sub-assembly of the cores ,is eliminated, and handling of the cores is reduced, to

aminimum.

Heretofore conventional coring arrangements .and methods of assembling engine cores have required the forming, handling and assembling of a multiplicity of coresto form a coring assembly for a cylinder head. For example, the cylinder heads of six-cylinder overhead valve internal combustion engines of the in-line type have conventionally required the use of approximately 11 cores. -Axcomparati-vely large amount of core sand and binder must be usedwithcomplex coring assemblies of this type. ,Moreover, the conventional coring arrangements here- -tofore used have required sub-assembly and pasting of .the1 cores. Each of these cores is subject to some breakage=due to handlingmf course, and whenever water-jacket cones arepasted together, as is conventionally done, there are numerous instances in, which thin fins of metal retmain. Whenthese fins, protrude into water jacket passages, they tend to restrict circulation and interfere with l the proper-operation of the engine. Removal of such @metahflashingis very difiicult 01' in. many instances impossible.

:A'principal object of the present invention, therefore, "is to provide a .cylinder head coring arrangement and i method; for assemblingthe cores in which the number of 1 coresfirequiredtis greatly decreased, sub-assembly, naill ting and. pasting of the co-resare eliminated, and the amounts of core sand and'binder required are substantially-reduced. These factors result in lower foundry costs savings being-effected both in materials and personnel.

vAtfurther-objecfiot this invention is to: provide a mold and coring assembly which forms a sounder cylinder head'casting duer to the effective use of green sand in the 1 mold as a substitutefor large slab cores. Since practicallythe-entire outside surface of the casting is surrounded by green sand -duri-ngmetal pouring operations, the quality of the casting is improved due to the absence of volatile constituents and the high porosity of' the green sand as comp'aredwith baked core materials.

The above and otherobjects are attained in accord- -ancewith the present invention by a cylinder block coring assemblyin which a singlewater jacket core replaces thetwo water'jacket core halves previously used and which required pasting together. This invention also employs a single intake and exhaust port-defining core rather than the multiplicity of such port cores heretofore used. Moreover, the-typical side slab core normally used in casting in-line engines is eliminated since the function of the conventional side slab core is performed "in the present instance by portions of the port core and thegreen' sand in *themold. Likewise, as hereinbefore indicated, this invention eliminates the conventional large base slab core or combustion chamber slab core and instead uses the green molding sand in the drag half of the fiask to full advantage, thereby further reducing operating costs.

'Other objects and advantages of this invention will more fully appear from the following detailed description of a preferred embodiment of the invention shown in the accompanying drawings, in which:

Figure lvis a perspective view showing the cores employed in a conventional coring arrangement for casting a cylinder head of an in-line, six-cylinder internal combustion engine of the overhead valve type;

Figure 2 is a perspective view showing the two cores used in accordance with the present invention to form a cylinder head of an in-line six-cylinder internal combustion ,engineof the overhead valve type;

:Figure 3 isa perspective view showing the relative positions: of theport core and water jacket core after these, cores have been assembled;

Figure 4 is a partially schematic, phantom end view, with parts broken away and in section, of a six-cylinder in-Iine gasoline engine of the overhead valve type showing agcylindenhead formed by a coring assembly intaccordance. with the present invention;

Figured is a fragmentary-sectional view of a cylinder head of the type shown in Figure 4-; and

Figure 6 is a sectional view through a green sand mold and the assembled cores of Figures 2 and 3 used to form the cylinderheadcavities and walls shown in Figure 5.

Referring more particularly to the drawings, in Figure 11 is shown the relatively complicated coring system heretofore conventionally used in casting cylinder heads for an in-line sixvcylinder engine of the overhead valve type.

:It will-be noted-that this arrangement consists of a multiplicity of cores including a combustion chamber slab core or base slab core '10, a lower water jacket core 12,

,upperwaterjacket core 14, side slab core 16, four exhaust port cores, 18,120, 22 and 24, and three intake port cores reversed end-for-end with respect to the other cores. In

' the: position shown, the arrangement of the various core can be readily seen.

prints and recesses in the combustion chamber slab core As the name implies, the combustion chamberslab core forms the depressions required in the bottom wall ofzthe cylinder head for the combustion "chambers and cooling water ports.

"When the .port cores are properly located in the mold,

: the end exhaust port cores 18 and 24 seat in slots 36 and -38,-respectively, in the upper surface of the vertically ex- -tending sidewall 40 of the combustion chamber slab core-10 and extend into the outermost transverse recesses slot-46 in the wall 40 and its forked end extending into transverse openings or recesses 48 in the upper surface of the lower water jacket core. Likewise, the intake port cores 26, 28 and 30 are located so that their outer ends engage corresponding slots 59 in the upper surface of wall 40 and their T-shaped inner ends extend through the-recesses 52 in the lower water jacket core. The core locators 54 which-depend from the ends of the port cores seat incorresponding. mating recesses or core prints 56 provided in the upper surface of the combustion chamber t is immaterial.

3 slab core, thus properly positioning the port cores and maintaining the spatial separation between the lower water jacket core and the port cores. Each of the port cores normally is pasted to the wall of the base slab core in which it is supported.

After the port cores are in position over the lower water jacket core and on the combustion chamber slab core, the upper water jacket core 14 is placed over the port cores and the lower water jacket core 12. The upper water jacket core is then pasted and/or nailed to the mating ground surfaces of the lower water jacket core with the various port cores 18, 20, 22, 24, 26, 28 and 30 located between them. Likewise, the lower water jacket core is normally pasted to the upper surface of the combustion chamber slab core.

Rather than following the exact procedure described above, however, the port cores first can be initially assembled between the two water jacket cores, the latter next pasted and/or nailed together, and the formed subassembly then pasted in position on the base slab core. However, this alternative method is normally more difiicult and, unless great care is exercised in placing the assembly on the combustion chamber slab core, edges of the port cores may be broken or chipped.

'The resultant coring assembly is then positioned on the ,green sand in the drag half of a mold, and the side slab core 16 is located in the mold so that one side 32 of this core abuts an outer side surface 34 of the combustion chamber slab core. If desired, transfer of the coring assembly to the mold may be accomplished by means of a core transfer fixture. Alternatively, the side slab core may be placed in position with respect to the other cores before the cores are placed in a transfer fixture and deposited in the mold. The cope half of the mold is then placed over the drag half, thus completing the mold and coring assembly.

When the above-described conventional coring arrangement for a cylinder head of an overhead valve, in-

line, six-cylinder gasoline engine is compared with the two or three cores which constitute the coring assembly in accordance with the present invention, the advantages of the latter with respect to number of cores, ease of assembly, cost, etc., are readily apparent. As shown in Figure 2, the new and improved coring arrangement includes only a water jacket core 58, a front port core 60 and a rear port core 62. If desired, the two port cores may be combined into a single core. For convenience in assembling the cores, however, the port cores are preferably separate.

Referring to Figures 2 and 3, these cores are preferably assembled in the following manner. First the water jacket core 58 is placed in proper position on the green sand in the drag half of the mold. The front port core 60 and the rear port core 62 are then fitted into the water jacket core in the manner shown in Figure 3, with the exhaust port-defininging arm portions 66, 68, 70 and 72 extending into the openings 74, 76, 78 and 80, respectively, in the central vertical wall of the water jacket core. Likewise, the intake port-defining arm portions 84, 86 and 88 extend into the similar openings 90, 92 and 94, respectively, in the side of the water jacket core. Since these arm portions are somewhat curved, this assembling procedure may be easily accomplished by rocking" the port cores 60 and 62 into position with an arcuate or curvilinear movement. On the other hand, if the aforementioned curvature of the arm portions is only slight, these arm portions may be inserted into the aforementioned openings in the water jacket core by mere translational movement of the port cores. The order in which the two port cores are placed in position However, the adjacent ends 102 of the longitudinally reinforcing or connecting portions 100 of these two cores must abut one another as shown.

Longitudinally extending core print projections or core locators 96 and 98 may be provided at one or both ends of the water jacket core. Such core locators engage corresponding core prints or depressions formed in the green sand in the drag half of the mold. In the embodiment of the water jacket core shown in the drawings, the core locator 96 at the front end of the water jacket core is of large size and performs the dual function of both properly locating the core with respect to the mold and aiding in forming the end contour of the cylinder head casting. The engagement of the core locators with corresponding core prints in the green sand assists in maintaining the proper spatial separation between the water jacket core, the port core, and the mold.

After the cores are assembled in the above manner on the green sand in the drag, the cope half of the mold is placed in position over the drag and assembled cores. The resultant arrangement, which is shown in Figure 6, will be hereinafter described in greater detail.

In the embodiment of the invention shown in the drawings, the front port core 60 and the rear port core 62 each forms both intake ports and exhaust ports, as well as aiding in forming one side contour of the cylinder head casting. If desired, these port cores may also be provided with laterally and/or vertically extending end wall portions for manufacturing purposes. The combustion chambers, spark plug pockets, rocker arm pockets, and the remainder of the outside contour are formed by the green sand in the mold.

It will be understood, of course, that the above-outlined procedure for assembling the two or three cores can be altered somewhat and the coring arrangement I handled in a core transfer or assembly fixture. Thus the cores can be assembled in a similar manner within a conventional type of core transfer fixture which is adapted to properly handle this simplified coring arrangement. The transfer fixture and the cores assembled therein can then be transported to the drag half of the green sand mold, and the fixture removed to deposit the core assembly in position in the mold. Moreover, these cores may be designed to be assembled in the reverse manner, if desired, and the molten casting metal can then be poured around the cores while the latter are in what I ing operations to provide perfectly flat mating surfaces are likewise unnecessary. Moreover, the two mating water jacket cores which are conventionally employed tend to separate upon pouring, usually resulting in the formation of undesirable fins. The present coring arrangement, on the other hand, substantially reduces the problem of finning and its attendant difficulites.

port-defining arm portions in proper alignment.

It will be noted that the exhaust port-defining arm portions 66 and 68 and the intake port-defining arm portions 84' and 86 of front port core 60' are rigidly interconnected by relatively heavy supporting bar portions 100. Likewise, exhause port-defining arm ports 70 and 72 and intake port-defining arm portion 88 of rear port core 62 are similarly interconnected. In this manner the seven separate port cores heretofore used and the vertically extending outer side portion 40 of the combustion chamber slab core previously employed are combined into only two cores. Thus it will be noted that the port cores 60 and 62 form all the intake ports 122 and exhaust ports 124 of the cylinder head casting 126 shown in Figures 4 and 5.

The longitudinally extending, supporting or connecting bar portions of the port core retain the various 'cordingly, if the core prints"inthe"greensand'mol'd are formed with sufiicient precision, it is possible toeliminate part or all of the connecting bar portions and to use s'epar'atesmall port cores instead. Such anarrang'ementwould make the use 'of an assembling fixture even more desirable than ifonly 'the two cores are used.

However, the elimination of the 'relativelysmall amount of core 'sand and binder-required to form the connecting portions 100 normally does not warrant the use "of separate cores in view "of the greater assembly and alignment'problems which attend the'use of the latter arrangement.

Referring now fo'Figu're 6, which shows the final cylinder-head mold and coring assembly immediately before pouring the molten casting metal, it will be'observ'ed that 'the port cores, such as front port core 60, are

supported on the green sand 104 in the drag half of 'suchas arm 68 of the port core60, with slight recesses "1 12 in the green sand in the drag half of the flask and by meansof the depending ridges or pr0jections 114 on the connecting portions of the port c'o're. These ridges mate with corresponding core prints 116 in the green sand in the drag and thereby function as core locators.

half of the flask similarly engages the top andside surfaces of the supporting or connecting bar portions 100 of the port cores 60 and 62. These bar portions preferably have their outer side surfaces 120 sloping slightly inwardly from the mold parting line 128 in order t facilitate positioning of the port core in the drag half of the mold and to prevent attrition between this core and the green sand of the cope when the latter is lower-ed into position over the cores.

Various modifications in the arrangement and details of the embodiment of the invention described and shown herein will be apparent to those skilled in the art and are contemplated as within the scope of the present invention as defined in the following claims.

I claim:

1. A coring assembly for use in casting a cylinder head of an overhead valve engine, said assembly comprising an elongated water jacket core having a generally flat base portion and an integral upper portion extending laterally over only a portion of said base portion, said upper portion having a longitudinally extending, generally vertical inner wall provided With a plurality of openings which extend downwardly through said base portion, and a combination intake and exhaust port core provided with a plurality of generally lateral extensions for forming intake and exhaust ports, said extensions fitting into said openings and being spatially separated from the wall of the water jacket core defining said openings.

2. A coring assembly for use in casting a cylinder head of an in-line engine of the overhead valve type, said assembly comprising an elongated water jacket core formed of core sand and a suitable binder, said water jacket core having an upstanding longitudinally extending side Wall portion and a flat base portion, said water jacket core being provided with a plurality of openings extending laterally through the inner side of said wall portion and being curved downwardly through the base of said core, and a plurality of elongated combined intake and exhaust port cores formed of core sand and a suitable binder positioned adjacent and parallel with the side'of said waterjacket core providedwit'lrsaid openings,"said port core's being "in longitudinal align- "ment 'and'having adjacente'nd surfaces in abutment, each of said port cores being provided-with a plurality'of intake and exhaust port-defining armportions extending laterally and downwardly -'-through' said openings, said for forming combustion chambers, spark"plug pockets and rocker 'a'rm pockets, an'elongated Water jacket core positioned ontheg'reen sand inthe drag half of the mold beneath the cope half of the mold, said water jacket core having a generally flat'base portion and a generally verticallyflextending upper portion, said upper portion having "a generally vertical side wall extending substantially'the entire length of said core and being provided with a plurality of laterally" extending and downwardly curved passages, said water jacket 'core'being provided with a longitudinally extending core locator at each end thereof engaging mating core printsformed in the green sand'in the drag half of the 'mold,-and an elongated combined intake and exhaust port core positioned between said mold-halves and provided witha plurality offcu'rved arm port-ions extendingthrough said passages,

'sai'd'arm portions being spatially separated from the "wallsof said'passages for formin'g intakeand exhaust ports in said cylinder head, "free ends of said armportions being seated on upstanding projections formed on the upper surface of the green sand in the drag half of the mold.

4. A foundry mold and coring assembly for use in forming a cylinder head casting for an internal combustion en ine, said assembly comprising a drag half of a mold formed of green sand and provided with a longitudinally extending core print in its upper surface, an elongated water jacket core positioned'on said green sand, said water. jacket core having a generally flat base portion and an integral generally upwardly extending portion having a plurality of openings formed in an inner wall thereof, said openings extending generally laterally relative to the cylinder head to be formed and downwardly through said base portion, an elongated combined intake and exhaust port core positioned on said green sand parallel with and adjacent said water jacket core, said port core having a longitudinally extending core locator formed on its lower surface engaging said core print, said port core also being provided with intake and exhaust port-defining extensions projecting generally laterally and downwardly through said openings and formed of a shape generally similar thereto, said extensions being spatially separated from the walls of said water jacket core defining said openings, free ends of said extensions being seated on upwardly extending projections formed on the green sand in the drag half of the mold beneath the water jacket core positioned thereon, and a cope half of a green sand mold positioned over the drag half of said mold and the cores assembled thereon.

5. A foundry mold and coring assembly for use in casting a cylinder head for an internal combustion engine, said assembly comprising a drag half of a mold formed of green sand, an elongated water jacket core formed of core sand and a suitable binder positioned on said green sand, said water jacket core having a generally fiat base portion and a generally upwardly extending portion integral with said base portion, said water jacket core being provided with a plurality of passages extending through an inner wall of said upwardly extending portion generally laterally relative to the cylinder head to be cast and downwardly through said base portion, a plurality of elongated combined intake and exhaust port cores formed of core sand and suitable binder positioned on said green sand parallel with and immediately adjacent the one side of said Water jacket 1 ing seated on upwardly extending projections formed on the green sand in the drag half of the mold beneath the water jacket core positioned thereon, and a cope half of a green sand mold positioned over the drag half of said mold and the cores asembled thereon.

6. A method of assembling cores for use in casting a cylinder head of an internal combustion engine which comprises placing an elongated water jacket core on the upper surface of green sand in the drag half of a mold, and positioning an elongated intake and exhaust port core on said green sand adjacent and parallel with one side of said water jacket core with laterally extending port-defining arm portions of said port core projecting through openings in said water jacket core and the free ends of said portions contacting said green sand beneath said water jacket core.

7. A method of forming a mold and coring assembly for use in casting a cylinder head of an internal combustion engine, said method comprising inserting a curved port-defining portion of a port core into an opening in a side of an elongated water jacket core, placing said assembled port core and water jacket core in position on v green sand in a drag half of a flask so that an end of said port-defining portion contacts an upwardly extending projection on said green sand, and thereafter positioning a cope half of a green sand mold over the resultant coring assembly and drag half of the mold.

8. A method of casting a cylinder head of an in-line internal combustion engine of the overhead valve type, said method comprising inserting a curved port-defining portion of a port core through an opening in a side of an elongated water jacket core, placing said assembled port core and water jacket core in position on green sand in a drag half of a metal flask so that a free end of said port-defining portion contacts a projection on the upper surface of said green sand beneath said water jacket core and a portion of said port core opposite said free end is seated in a core print formed in the upper 7 surface of said green sand adjacent said water jacket core, thereafter positioning a cope half of a green sand mold over said drag half and asembled cores, pouring molten casting metal around said cores into the mold cavity formed between the drag half and the cope half of the green sand mold, and permitting said molten metal to solidify.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Foundry Practice, by Palmer, Third Edition, pages -198. 

